Kraken, or krakken, are mighty aquatic minions of summoned by him from the Abyssal Maw in the Elemental Plane. Two types of "kraken" appear to exist. The first type are giant squid-like creatures with tentacles. The second type are more fish-like with giant fins and smaller in size.
In known history, the giant squid-like type has appeared four times. Once to destroy the Gurubashi Empire, as is told in The Fall of Gurubashi book. A second sighting came in the time anomaly, when one tried to grab Rhonin. This kraken was fifty feet in length.. Third one was when small group of naga tried to kill, or at least slow down Korialstrasz in his flight to Grim Batol. The fourth attacks the player on their journey to Vashj'ir a short while after they board the mercenary vessel.
The giant squid-like type of kraken are older than mortal races, huge towers of power, so huge that "jungles of kelp swayed through their limbs, and leviathans swam through bodies". It is told that "They remembered when the Old Ones ruled and when the Travelers came and cast them down. They remembered when magic was new." However, they still can be hurt by powerful magic.
A Kraken within the Serpentshrine Caverns has the name The Lurker Below. It is unknown if it is only a name given to the creature or actually another name for the fish-like Kraken in general.